Username already taken?

On the first attempt to create a user, it failed... this happened with a few usernames until I found a post suggesting I kill nscd then try again. That worked fine... HOWEVER now those usernames do not show up in CPanel or /etc/passwd, but I can't seem to reuse those names.

How can I tell cpanel to forget those usernames and allow me to create accounts with them?

Here's a cut/paste from cpanel when the accounts were not being properly set up...